US10456249B2 - Prosthetic heart valve with paravalvular leak mitigation features - Google Patents

Abstract

A prosthetic heart valve includes a collapsible and expandable stent with a valve assembly disposed therein. A first cuff is positioned on the lumenal or ablumenal surface of the stent. A second cuff is positioned radially outward of the stent and the first cuff. The second cuff may include apertures that allow blood to pass through the second cuff into the spaces between the first and second cuffs. The second cuff may include a proximal edge with a plurality of notches that may be closed to create puckered areas in the second cuff to facilitate the movement of blood in the spaces between the first and second cuffs. The stent may include struts adjacent the second cuff that bow radially inwardly to create additional space for blood to flow in the spaces between the first and second cuffs.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of the filing date of U.S. Provisional Patent Application No. 62/394,837 filed Sep. 15, 2016, the disclosure of which is hereby incorporated by reference herein.

BACKGROUND OF THE DISCLOSURE

The present disclosure relates to heart valve replacement and, in particular, to collapsible prosthetic heart valves. More particularly, the present disclosure relates to collapsible prosthetic transcatheter heart valves which minimize or reduce paravalvular leaks.

Prosthetic heart valves that are collapsible to a relatively small circumferential size can be delivered into a patient less invasively than valves that are not collapsible. For example, a collapsible valve may be delivered into a patient via a tube-like delivery apparatus such as a catheter, a trocar, a laparoscopic instrument, or the like. This collapsibility can avoid the need for a more invasive procedure such as full open-chest, open-heart surgery.

Collapsible prosthetic heart valves typically take the form of a valve structure mounted on a stent. There are two common types of stents on which the valve structures are ordinarily mounted: a self-expanding stent and a balloon-expandable stent. To place such valves into a delivery apparatus and ultimately into a patient, the valve is first collapsed or crimped to reduce its circumferential size.

When a collapsed prosthetic valve has reached the desired implant site in the patient (e.g., at or near the annulus of the patient's heart valve that is to be replaced by the prosthetic valve), the prosthetic valve can be deployed or released from the delivery apparatus and re-expanded to full operating size. For balloon-expandable valves, this generally involves releasing the valve, assuring its proper location, and then expanding a balloon positioned within the valve stent. For self-expanding valves, on the other hand, the stent automatically expands as a sheath covering the valve is withdrawn.

After implantation, imperfect sealing between the cuff and the site of implantation may cause complications such as paravalvular leakage (“PV leak”), or blood flowing through one or more gaps formed between the structure of the implanted valve and cardiac tissue.

BRIEF SUMMARY

According to one aspect of the disclosure, a prosthetic heart valve for replacing a native valve includes a stent extending in an axial direction between an inflow end and an outflow end and having circumferential rows of cells formed by cell struts, the stent having a collapsed condition and an expanded condition. A valve assembly is disposed within the stent. A first cuff is disposed on a lumenal surface of the stent. A second cuff has a proximal edge facing toward the inflow end of the stent and a distal edge facing toward the outflow end of the stent, the second cuff being annularly disposed about one of the circumferential rows of cells and positioned radially outward of the first cuff and the stent. An ablumenal surface of selected cell struts forming the one circumferential row of cells has a concave curvature in a length direction of the selected cell struts of the stent when the stent is in the expanded condition.

According to another aspect of the disclosure, a prosthetic heart valve for replacing a native valve includes a stent extending in an axial direction between an inflow end and an outflow end, the stent having a collapsed condition and an expanded condition. A valve assembly is disposed within the stent. A first cuff is disposed on a lumenal surface of the stent. A second cuff has a proximal edge facing toward the inflow end of the stent and a distal edge facing toward the outflow end of the stent. The second cuff is annularly disposed about the stent and positioned radially outward of the first cuff and the stent. The second cuff includes a plurality of notches at spaced apart locations along the proximal edge, each of the notches defining a void in the proximal edge of the second cuff. The second cuff has an initial configuration in which the voids render the proximal edge of the second cuff discontinuous, and a gathered configuration in which the voids are closed so that the proximal edge of the second cuff is substantially continuous. The proximal edge of the second cuff in the gathered configuration has a length that is less than the length of the proximal edge of the second cuff in the initial configuration. The second cuff is coupled to at least one of the stent and the first cuff so that in the expanded condition of the stent, the second cuff is in the gathered configuration.

According to a further aspect of the disclosure, a stent extending in an axial direction from an inflow end to an outflow end has a collapsed condition and an expanded condition. A valve assembly is disposed within the stent. A first cuff is annularly disposed on a lumenal or ablumenal surface of the stent. A second cuff has a proximal edge facing toward the inflow end of the stent and a distal edge facing toward the outflow end of the stent, the second cuff being annularly disposed about the stent and positioned radially outward of the first cuff and the stent. The second cuff includes a plurality of apertures.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the presently disclosed prosthetic heart valve may be more fully understood with reference to the following detailed description when read with the accompanying drawings, in which:

FIG. 1 is a front view of a collapsible prosthetic heart valve according to the prior art;

FIG. 2 is a highly schematic transverse cross-sectional view of the prior art prosthetic heart valve implanted in a patient, taken along line2-2 ofFIG. 1;

FIG. 3A is a schematic view of a stent according to an embodiment of the disclosure in a flattened condition with an inner cuff and an outer cuff;

FIG. 3B is a highly schematic transverse cross-sectional view of a prosthetic heart valve including the stent and outer cuff ofFIG. 3A implanted in a patient;

FIG. 3C is a highly schematic view of retrograde blood flowing into a portion of the outer cuff on the stent ofFIG. 3A;

FIG. 3D is a side view of a portion of the outer cuff on the stent ofFIG. 3A in an expanded condition;

FIG. 4A is a highly schematic longitudinal cross-sectional view of a stent according to another embodiment of the disclosure;

FIG. 4B is a side view of a portion of an outer cuff on the stent ofFIG. 4A in an expanded condition;

FIG. 4C is a highly schematic view of retrograde blood flowing into a portion of the outer cuff on the stent ofFIG. 4A;

FIG. 4D is a side view of a portion of an outer cuff on the stent ofFIG. 4A in a collapsed condition;

FIG. 5A is a side view of a portion of an outer cuff on an alternate embodiment of a stent in an expanded condition;

FIG. 5B is a side view of a portion of the outer cuff on the stent ofFIG. 5A in a collapsed condition;

FIG. 5C is a side view of a portion of the outer cuff on an alternate embodiment of a stent in an expanded condition;

FIG. 5D is a side view of a portion of the outer cuff on the stent ofFIG. 5C in a collapsed condition;

FIG. 6A is a side view of an outer cuff with notches in a flattened condition according to another embodiment of the disclosure;

FIG. 6B is a side view of the outer cuff ofFIG. 6A after connecting portions of the outer cuff adjacent the notches;

FIG. 6C is a highly schematic view of the outer cuff ofFIG. 6A coupled to the stent and/or inner cuff ofFIG. 3A;

FIG. 6D is a side view of an outer cuff with notches in a flattened condition having an alternate pattern to that shown inFIG. 6A;

FIG. 6E is a side view of the outer cuff ofFIG. 6D after connection portions of the outer cuff adjacent the notches;

FIG. 6F is a highly schematic view of the outer cuff ofFIG. 6D coupled to the stent and/or inner cuff ofFIG. 3A;

FIG. 7A is a side view of an outer cuff with a plurality openings in a flattened condition; and

FIG. 7B is a highly schematic view of the outer cuff ofFIG. 7A coupled to the stent and/or inner cuff ofFIG. 3A.

DETAILED DESCRIPTION

As used herein, the term “inflow end,” when used in connection with a prosthetic heart valve, refers to the end of the heart valve through which blood enters when the valve is functioning as intended. As used herein, the term “proximal” refers to the inflow end of a prosthetic heart valve or to elements of a prosthetic heart valve that are relatively close to the inflow end, and the term “distal” refers to the outflow end of a prosthetic heart valve or to elements of a prosthetic heart valve that are relatively close to the outflow end. The term “outflow end,” when used in connection with a prosthetic heart valve, refers to the end of the heart valve through which blood exits when the valve is functioning as intended. As used herein, the terms “generally,” “substantially,” and “about” are intended to mean that slight deviations from absolute are included within the scope of the term so modified. Like numbers refer to similar or identical elements throughout. When used herein in the context of a prosthetic heart valve, or a component thereof, the “lengthwise direction” or “axial direction” refer to a direction along a longitudinal axis passing through the center of the stent or heart valve. When used herein in the context of a prosthetic heart valve, or a component thereof, the “circumferential direction” refers to a direction extending along the circumference of the prosthetic heart valve in a direction orthogonal to the longitudinal axis.

FIG. 1 shows a collapsible stent-supportedprosthetic heart valve100 in an expanded condition according to the prior art. Theprosthetic heart valve100 is designed to replace the function of a native aortic valve of a patient. Theprosthetic heart valve100 includes a stent constructed as aframe102. Thestent102 extends from an inflow orannulus end130 to an outflow oraortic end132 along a lengthwise or longitudinal axis L, and includes an annulus section104 adjacent theinflow end130 and anaortic section142 adjacent theoutflow end132. The annulus section104 has a relatively small cross-section in the expanded condition, while theaortic section142 has a relatively large cross-section in the expanded condition. The annulus section104 may be in the form of a cylinder having a substantially constant diameter along its length. Atransition section141 may taper outwardly from the annulus section104 to theaortic section142. Each of the sections of thestent102 includes a plurality ofcells112 connected to one another in one or more annular rows around thestent102. For example, as shown inFIG. 1, the annulus section104 may have two annular rows ofcomplete cells112 and theaortic section142 and thetransition section141 may each have one or more annular rows of complete orpartial cells112. Thecells112 in theaortic section142 may be larger than thecells112 in the annulus section104. Thelarger cells112 in theaortic section142 may better enable theprosthetic valve100 to be positioned without the structure of thestent102 interfering with blood flow to the coronary arteries. At least partly due to the shape ofcells112, thestent102 elongates in the direction of axis L ascells112 collapse when thestent102 is transitioned from the expanded condition to the collapsed condition.

Thestent102 may include one ormore retaining elements118 at theoutflow end132, the retainingelements118 being sized and shaped to cooperate with retaining structures provided on a deployment device (not shown). The engagement of the retainingelements118 with the retaining structures on the deployment device may help maintain theprosthetic heart valve100 in assembled relationship with the deployment device, minimize longitudinal movement of the prosthetic heart valve relative to the deployment device during unsheathing or resheathing procedures, and help prevent rotation of the prosthetic heart valve relative to the deployment device as the deployment device is advanced to the target location and during deployment. One such deployment device is shown in U.S. Patent Publication No. 2012/0078352, the entire contents of which are hereby incorporated by reference herein.

Thestent102 may also include a plurality of commissure attachment features or points116 for mounting the commissures of the valve assembly to thestent102. As can be seen inFIG. 1, eachcommissure attachment feature116 may lay at the intersection of fourcells112, two of thecells112 being adjacent one another in the same annular row, and the other twocells112 being in different annular rows and lying in end to end relationship. The commissure attachment features116 may be positioned entirely within the annulus section104 or at the juncture of annulus section104 andtransition section141, and may include one or more eyelets which facilitate the suturing of the leaflet commissures to the stent. Thestent102 may be formed as a unitary structure, for example, by laser cutting or etching a tube of a super elastic and/or shape memory metal alloy such as a nickel-titanium alloy of the type sold under the designation nitinol. Such a unitary structure can also be referred to as a “non-woven” structure, in that it is not formed by weaving or winding one or more filaments.

Theprosthetic heart valve100 includes avalve assembly140 positioned at least partially in the annulus section104. The valve assembly includes acuff106 and a plurality ofleaflets108 that collectively function as a one way valve by coapting with one another. AsFIG. 1 illustrates a prosthetic heart valve for replacing a native aortic valve, the prosthetic heart valve is shown with threeleaflets108. Two leaflets join one another at each of three commissures. When implanted at the native aortic valve annulus, blood flows from theinflow end130,past leaflets108, and toward theoutflow end132. This occurs when the pressure in the left ventricle is greater than the pressure in the aorta, forcing theleaflets108 to open. When the pressure in the aorta is greater than the pressure in the left ventricle, theleaflets108 are forced closed and coapt with one another along free edges of theleaflets108, blocking blood from flowing through the prosthetic heart valve in a retrograde fashion from theoutflow end132 to theinflow end130. Thevalve assembly140 may be mounted to thestent102 by suturing the commissures of theleaflets108 to each of the three commissure attachment features116 and suturing other portions of theleaflets108 to thestent102 and/orcuff106, or by other methods known in the art. It will be appreciated that the prosthetic heart valves according to aspects of the disclosure may have a greater or lesser number ofleaflets108 and commissure attachment features116 than shown inFIG. 1 and described above. Eachleaflet108 may define a leaflet belly B, indicated with broken lines inFIG. 1. The leaflet belly B is the portion ofvalve assembly140 above whichleaflets108 are free to move radially inwardly to coapt with one another along their free edges.

Although thecuff106 is shown inFIG. 1 as being disposed on the lumenal or inner surface of the annulus section104, thecuff106 may be disposed on the ablumenal or outer surface of annulus section104, or may cover all or part of either or both of the lumenal and ablumenal surfaces of the annulus section104. As is shown inFIG. 1, in one example the entirety of thevalve assembly140, including the leaflet commissures, is positioned in the annulus section104 of thestent102. When open, the leaflets may extend further into thetransition section141 or may be designed such that they remain substantially completely within the annulus section104. In this embodiment, substantially the entirety of thevalve assembly140 is positioned between theinflow end130 ofstent102 and the commissure attachment features116, and none of the valve assembly is positioned between the commissure attachment features116 and theoutflow end132 of thestent102.

In operation, the embodiment of theprosthetic heart valve100 described above may be used to replace a native heart valve, such as the aortic valve, a surgical heart valve, or a heart valve that has undergone a surgical procedure. Theprosthetic heart valve100 may be delivered to the desired site (e.g., near a native aortic annulus) using any suitable delivery device. During delivery, theprosthetic heart valve100 is disposed inside the delivery device in the collapsed condition. The delivery device may be introduced into a patient using any known procedures, such as a transfemoral, transapical, subclavian or transseptal approach. Once the delivery device has reached the target site, the user may deploy theprosthetic heart valve100. Upon deployment, theprosthetic heart valve100 expands into secure engagement within the native aortic annulus. When theprosthetic heart valve100 is properly positioned inside the heart, it works as a one-way valve, allowing blood to flow in one direction and preventing blood from flowing in the opposite direction.

FIG. 2 is a highly schematic transverse cross-sectional illustration of theprosthetic heart valve100 havingleaflets108 disposed within thenative valve annulus250, taken along line2-2 shown inFIG. 1. As seen inFIG. 2, the substantially circular annulus section104 of thestent102 is disposed within a non-circularnative valve annulus250. At certain locations around the perimeter of theprosthetic heart valve100,gaps200 form between theheart valve100 and thenative valve annulus250. Blood flowing through these gaps and around the outside of thevalve assembly140 of theprosthetic heart valve100 can result in PV leak or regurgitation and other inefficiencies which can reduce cardiac performance. Such improper fitment may be due to suboptimal native valve annulus geometry due, for example, to calcification of thenative valve annulus250 or due to unresected native leaflets.

FIG. 3A illustrates astent302 of a prosthetic heart valve according to an aspect of the disclosure.Stent302 may be used in a prosthetic heart valve that is similar or identical toprosthetic heart valve100 described above with certain exceptions. For example,annulus section304 ofstent302 may include three rows ofcells312 instead of two rows, althoughstent302 may alternatively include two rows ofcells312 inannulus section304. It should be understood that, while commissure attachment features316 ofstent302 are illustrated as open rectangles, the commissure attachment features316 may take a form similar to commissure attachment features116, or any other suitable form including any number of rows or columns of eyelets and/or eyelets of different sizes and/or shapes positioned in any arrangement on the commissure attachment feature. Acuff306 similar or identical tocuff106 may be positioned on the lumenal and/or ablumenal surface ofstent302. Althoughcuff106 is shown as scalloped at its inflow end,cuff306 may have a straight inflow end rather than a scalloped one. In order to help eliminate PV leak, for example through thegaps200 shown inFIG. 2, additional material may be coupled to the exterior ofstent302 as anouter cuff350. In the illustrated example,outer cuff350 may have a substantially rectangular shape and may be wrapped around the circumference ofstent302 at its inflow end.Outer cuff350 may be positioned anywhere along the height ofstent302, so long as the proximal edge of the outer cuff is either at the proximal edge ofinner cuff306 or between the proximal and distal edges of the inner cuff, and the distal edge of the outer cuff is either at the distal edge of the inner cuff or between the proximal and distal edges of the inner cuff. With this positioning,outer cuff350 is positioned onstent302 so as to overlap in the longitudinal direction ofstent302 withinner cuff306.Outer cuff350 may be a single piece of material including aproximal edge352, twoside edges354,356, and adistal edge358. Preferably, theproximal edge352 ofouter cuff350 is coupled to thestent302 and/or to theinner cuff306 along a proximal edge of thestent302 and/or a proximal edge of theinner cuff306, for example by a continuous line of sutures (not shown), so that retrograde blood flow entering the space between theouter cuff350 and theinner cuff306 cannot pass in the retrograde direction beyond the combination of cuffs. In order to allow retrograde blood flow to enter the space between theouter cuff350 and theinner cuff306, thedistal edge358 may be attached at spaced apart locations to thestent302 and/or theinner cuff306. In the illustrated example, thedistal edge358 ofouter cuff350 is sutured tostent302 at attachment points S1 which are located at the intersection of eachcell312 in the proximalmost row of cells with anadjacent cell312 in that same row. In the illustrated example, since there are ninecells312 in the proximalmost row, there are nine separate points of attachment S1 where thedistal edge358 is coupled tostent302 and/orinner cuff306. Retrograde blood flow around the ablumenal surface ofstent302 may enter the pocket or space betweenouter cuff350 andinner cuff306 via the space between any two adjacent attachment points S1. Once retrograde blood flow enters this space, theouter cuff350 may tend to billow outwardly, helping to seal any of thegaps200 between the prosthetic heart valve and thenative annulus250. It should be understood that although the term “inner” is used in connection withcuff306, that is merely intended to indicate thatcuff306 is positioned radially inward ofouter cuff350. However,inner cuff306 may be located either on the lumenal or ablumenal surface ofstent302, or on both surfaces. It should be understood that inFIG. 3A, only part of the outline ofinner cuff306 is visible, as a bottom or proximal end ofinner cuff306 is positioned behindouter cuff350 in the view ofFIG. 3A.

Although described as a single piece of material above,outer cuff350 may comprise multiple pieces of material that in the aggregate form a similar shape and provide similar function to that described above forouter cuff350. Also, rather than being formed as a structure that is wrapped around the circumference ofstent302,outer cuff350 may be formed as a continuous tube without defining distinct side edges354,356. Preferably,outer cuff350 has an axial height measured fromproximal edge352 todistal edge358 that is approximately half the axial height of thecells312 in the proximalmost row ofstent302 as measured along the major axes of the cells between two apices when the cells are in an expanded condition. However, other heights ofouter cuff350 may be suitable, such as the full axial height of thecells312 in the proximalmost row of cells, or more or less than the full axial height ofsuch cells312. However, different heights ofouter cuff350 may result in a change of the position of attachment points S1. For example, ifouter cuff350 is formed with a height equal to the full axial height of thecells312 in the proximalmost row of cells, the attachment points S1 could be positioned at the distalmost apex ofsuch cells312. Still further, although theouter cuff350 is described above as separate from theinner cuff306, theouter cuff350 may be integral with theinner cuff306, the combined cuff wrapping around the inflow end ofstent302. With this configuration, theproximal edge352 ofouter cuff350 does not need to be sutured tostent302, although it still may be preferable to provide such attachment. Both theinner cuff306 and theouter cuff350 may be formed of the same or different materials, including any suitable biological material or polymer such as, for example, polytetrafluoroethylene (PTFE), ultra-high molecular weight polyethylene (UHMWPE), polyurethane, polyvinyl alcohol, polyester, silicone, or combinations thereof.

As shown inFIG. 3B, when a prosthetic heartvalve including stent302 andouter cuff350 is implanted into anative valve annulus250, retrograde blood flow may causeouter cuff350 to billow radially outward and fillgaps200. However, after retrograde blood flow passes thedistal edge358 ofouter cuff350 and enters the space between the outer cuff and theinner cuff306, that blood may not easily be able to migrate past the cell struts located between the inner and outer cuffs toward the proximal edges of the cuffs when certain conditions are present. This point is illustrated inFIG. 3C. As blood flows in the retrograde direction D around the ablumenal surface ofstent302, the blood can enter the space betweenouter cuff350 andinner cuff306 via the openings between attachment points S1, as described above. If a condition exists in whichouter cuff350 is taut whenstent302 is in the expanded condition, blood may not be able to pass across struts312cand312dinto the space of adjacent cells (or half-cells), such as those directly under attachment points S1. As shown inFIG. 3D, ifouter cuff350 is taut whenstent302 is in the expanded condition, there may be little or no open space betweenouter cuff350 and struts312c, as well as betweenouter cuff350 and struts312d. Even when subjected to the pressure causing retrograde blood to flow into the space betweenouter cuff350 andinner cuff306, little or none of that blood may migrate past cell struts312cand312dinto the restricted spaces RS. By providing additional and/or alternative structures as described in greater detail below, theouter cuff350 may be provided with an enhanced ability to billow outwardly to fillgaps200.

FIG. 4A shows a longitudinal cross-sectional view of astent402 that may be identical tostent302, with certain exceptions described below.Stent402 may be used with an inner cuff and outer cuff similar or identical toinner cuff306 andouter cuff350, respectively. In particular,stent402 may include two rows ofcells412 in an annulus section, withinner cuff306 andouter cuff350 coupled tostent402 in a similar or identical manner to that described in connection withstent302. However, whereas theannulus section304 ofstent302 may be substantially cylindrical when in the expanded condition, certain struts ofstent402 may be bowed radially inwardly. For example, struts412cand/or struts412dofcells412 in the proximalmost row of cells ofstent402 may be bowed, arched, or otherwise curved radially inwardly so that, whenstent402 is in the expanded condition, a center portion of each of thesecurved struts412c,412dis positioned radially inwardly of proximal and distal portions of those curved struts. The curvature ofstruts412cand/or struts412dmay be such that the terminal ends of these curved struts are positioned a substantially equal distance in the radial direction from the longitudinal axis ofstent402, and the center portions of these struts are positioned at a lesser distance in the radial direction from the longitudinal axis. The lumenal surface ofstruts412cand412dmay have a convex curvature along the entire length of the struts between their proximal and distal ends, with the ablumenal surface of those struts having a concave curvature along the entire length of the struts between their proximal and distal ends. With this configuration, as best seen inFIG. 4B, whenouter cuff350 is taut andstent402 is in the expanded condition, there is anopen space490 betweenstruts412candouter cuff350, as well as betweenstruts412dandouter cuff350, due to the curvature of those struts. As shown inFIG. 4C, retrograde blood may enter the space betweenouter cuff350 andinner cuff306 by flowing in the retrograde direction D between adjacent points of attachment S1 of thedistal edge358 ofouter cuff350 to thestent402 and/orinternal cuff306. The blood betweenouter cuff350 andinner cuff306 may readily flow acrossstruts412cand412din the directions D₁by way of theopen space490 betweenouter cuff350 and the center portions ofstruts412cand412d, so that any portion ofouter cuff350 adjacent agap200 may be able to billow outwardly to fill that gap. Although it is preferable that eachstrut412cand412din the proximalmost row of cells is curved as described above, providing a similar curvature to some but less than all of these struts, such as only struts412cand not struts412d, or only struts412dand not struts412c, may provide a similar benefit.Struts412cand412dmay be set to the desired shape in a similar or identical fashion as the remainder of thestent402 is shape-set, for example by heat-setting.

The shape ofstruts412cand412dmay be set so that the curvature described above completely or substantially remains whenstent402 is the collapsed condition. This feature may result in a reduction in the forces encountered upon loading the prosthetic valve into a delivery device in the collapsed condition. For example, as shown inFIG. 4D, portions ofouter cuff350 adjacent the curved portions ofstruts412cand412dmay nest or otherwise sit along thecurved struts412cand412d, which may reduce the overall bulkiness of the prosthetic heart valve in those areas. However, it should be understood that in this and other embodiments described herein, thestruts412cand/or412dmay take other shapes uponstent402 collapsing. For example, struts412cand412dmay become substantially parallel to a longitudinal axis of the stent when in the collapsed condition in some embodiments.

FIGS. 4A-D illustrate an embodiment ofstent402 in which thestruts412cand412din thecells412 in the proximalmost row of cells are curved or bowed radially inwardly along substantially the entire length of those struts. However, alternative shapes also may be suitable. For example,FIGS. 5A-B illustrate astrut412c′ of a stent and theouter cuff350 of a prosthetic heart valve that is identical in every way to the prosthetic heartvalve including stent402 andouter cuff350 described above, except for the curvature of the struts corresponding to struts412cand412d. In particular, althoughstruts412c′ are bowed radially inwardly so that a center portion of each strut is positioned radially inwardly of proximal and distal portions of that strut when the stent is in the expanded condition, thestruts412c′ are not curved along substantially their entire length. Rather, proximal and distal portions ofstruts412c′ may be positioned substantially within the same cylindrical surface of revolution about the longitudinal axis of the stent, which surface also includes the struts in other cells in the annulus section of the stent. In other words, the portion ofstruts412c′ that is bowed radially inward may be isolated to a center portion of the struts, with the proximal and distal portions lacking such curvature. Thus, the lumenal surface of the center portion ofstrut412c′ may have a convex curvature in the length direction of that strut, while the ablumenal surface of the center portion of the strut has a convex curvature in the same length direction. The proximal and distal end portions ofstrut412c′, however, may each be substantially straight in the length direction of the strut, and may be collinear. In this embodiment, the bowed portion of eachstrut412c′ and theouter cuff350 together define anopen space490′, generally similar toopen space490, that may allow for blood positioned betweenouter cuff350 andinner cuff306 to migrate acrossstruts412c′, even ifouter cuff350 is taut. Although not illustrated inFIGS. 5A-B, it should be understood that struts corresponding to struts412dmay have the same or similar shape and curvature asstruts412c′. Also, similar to the embodiment described in connection withFIGS. 4A-D, the curvature ofstruts412c′ (and the similarly shaped struts corresponding to struts412d) may result in a reduction in the forces encountered upon loading the prosthetic valve into a delivery device in the collapsed condition, where portions ofouter cuff350 nest or otherwise sit along the curved portions of the struts. Other benefits that may be provided by the embodiment shown inFIGS. 5A-B may include easier fabrication, the facilitation of proper resheathing of the valve during surgery if desired, and maintaining consistent outward radial force of the stent on the native anatomy.

A similar result to that achieved with thecurved struts412cand412c′ may be obtained without having the struts bow radially inwardly. For example, rather than shape-setting the struts to have a particular curvature to create open spaces between the struts and the outer cuff, the particular struts of interest may be formed with varying widths or thicknesses. For example,FIG. 5C illustrates astrut412c″ of a stent that is identical tostent402 in every aspect other than the shape of the struts corresponding to struts412cand412d.Struts412c″ (and the struts corresponding to struts412dof stent402) may be formed so that their center portions' have a reduced thickness or diameter compared to their proximal and distal portions. This may be accomplished, for example, by laser cutting or grit blasting struts412c″ (and the struts corresponding to struts412d) to have a reduced thickness. In order to createopen spaces490″, the thickness ofstruts412c″ should be reduced so that the proximal and distal portions of the struts extend farther radially outward than center portions of the struts. In other words, when thestent incorporating struts412c″ is in the expanded condition, the sides of thestruts412c″ forming a portion of the lumenal surface of the stent (toward the right inFIG. 5C) should have little or no curvature in the length direction of the struts, whereas the sides of the struts forming a portion of the ablumenal surface of the stent (toward the left inFIG. 5C) should be curved in the length direction of the struts. Thus, whereas all or portions ofstruts412cand412c′ have a concavely curved ablumenal surface and a convexly curved lumenal surface in the length direction of the struts, struts412c″ have a concavely curved ablumenal surface in the length direction of the struts, but a substantially straight lumenal surface in the length direction of the struts.

If a typical strut ofstent402 has a thickness of between about 0.015 and about 0.018 inches, the center portion ofstruts412c″ may have a thickness that is reduced by between about 0.004 and about 0.005 inches compared to the other struts (and compared to the proximal and distal ends ofstruts412c″. As shown inFIG. 5D, when thestent incorporating struts412c″ is transitioned to the collapsed condition,outer cuff350 may at least partially nest or sit within the axially curved surfaces ofstruts412c″. It should be understood that although particular shapes, for example of inward curves, are illustrated inFIGS. 4A-5D, any shape ofstruts412cand412d(or struts corresponding to struts412cand412d) that provides space between the strut and an adjacent cuff, whether an inner or outer cuff, may be suitable to increase blood flow across that strut and between the cuffs.

FIG. 6A illustrates anouter cuff550 that may be used, instead ofouter cuff350, with aninner cuff306 and a stent similar or identical tostent302.Outer cuff550 generally has a straight inflow orproximal edge552, correspondingly angled side edges554 and556, and a scalloped outflow ordistal edge558, and may be formed from any of the materials noted above for forming the other cuffs described herein, either from a single piece of material, from more than one piece of material, or as a single tubular member (i.e., without side edges554 and556).Outer cuff550 may be wrapped aroundstent302 withedges554 and556 sutured or otherwise attached to one another. Theproximal edge552 ofouter cuff550 may be attached to the inflow end ofstent302 and/or toinner cuff306, for example by a continuous line of sutures, so that theouter cuff550 is positioned at any height between the proximal and distal edges of theinner cuff306. It should also be understood that although other cuffs herein are shown with a straight distal edge, those cuffs may have a scalloped distal edge as shown inFIG. 6A, orouter cuff550 may have a substantially straight distal edge. Preferably, the attachment points couplingouter cuff550 tostent302 and/orinner cuff306 are positioned at the peaks ofdistal edge558, with the troughs not being directly coupled to the stent or the inner cuff.

Prior to attachment tostent302 and/orinner cuff306, the substantially straightproximal edge552 ofouter cuff550 may be interrupted by a plurality of spacednotches553. Eachnotch553 may be substantially triangular in shape with the base of the triangle (i.e., the base of the notch) positioned alongproximal edge552. Theproximal edge552 ofouter cuff550 has an end-to-end length L₁such that, ifouter cuff550 is wrapped into a tube so that edges554 and556 mate, the circumference of the proximal edge will have a greater length than the circumference of thestent302 at the position at whichouter cuff550 is intended to connect to the stent or inner cuff. Prior to attachment tostent302, thenotches553 may be closed by coupling the portions ofproximal edge552 adjacent eachnotch553 to one another, for example by sutures, adhesives, or any other suitable method, so that theproximal edge552 is substantially continuous without interruption. Because the portions ofproximal edge552 adjacent eachnotch553 are pulled together and coupled to one another, the length L₂of theproximal edge552 is reduced compared to the length L₁. The reduction in the length of theproximal edge552 upon closing thenotches553 is substantially equal to the aggregate length of the open bases of the notches. The length of the open base of eachnotch553 may be selected depending on, for example, the number of cells in thestent302 and the size of the prosthetic heart valve incorporating the stent and theouter cuff550. In the case of a 32 mm size valve having ninecells312 in the proximalmost row, the base of eachnotch553 may be between about 0.04 inches and 0.06 inches long, preferably about 0.05 inches long. Preferably, once the open bases ofnotches553 are closed, the resulting length L₂ofproximal edge552 is substantially equal to the circumference of the portion ofstent302 or the portion ofinner cuff306 to which theouter cuff550 will be attached. Because the length ofproximal edge552 decreases upon coupling together the portions of the proximal edge adjacent eachnotch553, the material ofouter cuff550 may gather at the positions of thenotches553 to form puckeredareas555, as shown inFIG. 6B.

As shown inFIG. 6C, thedistal edge558 ofouter cuff550 may be attached tostent302 and/orinner cuff306, for example on the ablumenal surface of the stent along the proximalmost row ofcells312, at attachment points S1, similar to the attachment ofouter cuff350 tostent302 and/orinner cuff306 as described in connection withFIGS. 3A-D. In particular, each peak ofdistal edge558 may be attached tostent302 and/orinner cuff306 at the locations at which twoadjacent cells312 in the proximalmost row of cells intersect one another, with the portions of the distal edge between attachment points S1 remaining detached from both the stent and the inner cuff. As shown inFIG. 6A, thenotches553 are preferably positioned so they are substantially aligned in the axial direction with the peaks of thedistal edge558 ofouter cuff550. With this configuration, once theouter cuff550 is coupled tostent302 and/orinner cuff306, the puckeredportions555 of the outer cuff are positioned betweenstrut312cof one cell and strut312dof a circumferentially adjacent cell in the proximalmost row of cells. The puckeredportions555 ofouter cuff550 reduce the tautness of, or increase the slack in,outer cuff550 at these positions, allowing for blood located between the outer cuff andinner cuff306 to more easily migrate in those locations. In particular, retrograde blood flowing into the space betweenouter cuff550 andinner cuff306 may more easily migrate acrossstruts312cand312ddue to the additional space provided by the puckeredportions555 of the outer cuff which, in turn, allows for the outer cuff to billow outwardly intogaps200 more completely.

As shown inFIG. 6C, the open bases ofnotches553 may be closed with a suture at attachment points S2 prior to coupling theouter cuff550 to thestent302 and/orinner cuff306. The sutures at attachment points S2 may be separate from a substantially continuous suture line coupling theproximal edge552 ofouter cuff550 to thestent302 and/orinner cuff306. However, other methods may be used to couple theproximal edge552 ofouter cuff550 to thestent302 and/orinner cuff306. In one example, the open bases ofnotches553 are not closed in a step that is separate from attaching theproximal edge552 of theouter cuff550 to thestent302 and/orinner cuff306. For example, theproximal edge552 ofouter cuff550 may be attached to thestent302 and/orinner cuff306 by a single continuous suture line, without providing separate sutures to close the open bases of thenotches553. In such a configuration, a suture is used to couple theproximal edge552 ofouter cuff550 to thestent302 and/orinner cuff306, and as the suture approaches anotch553, the user may gather portions of the proximal edge to close the open base of thenotch553 and continue the suturing so that an additional suture element is not needed to hold thenotches553 in the closed condition. It should be understood that once the portions of theproximal edge552 ofouter cuff550 adjacent eachnotch553 are coupled together, it may not be critical to ensure that the entire space of thenotch553 is completely sealed. For example, because thenotches553 are small and the cycling between systole and diastole is fast, small gaps may remain inouter cuff550 where thenotches553 are positioned without significant leakage of blood through those gaps. Allowing some amount of gap to remain innotches553 may even be beneficial. For example, leaving such gaps may provide openings for a user to eliminate air bubbles trapped betweenouter cuff550 andinner cuff306 prior to implanting the prosthetic valve into the patient.

In the embodiment ofouter cuff550 shown inFIGS. 6A-C, the outer cuff includes nine peaks and nine troughs, with ninenotches553 axially aligned with corresponding peaks, andstent302 includes ninecells312 in the proximalmost row of cells. Although it may be desirable to have this correspondence between peaks,notches553, andcells312, such correspondence is not necessary. For example, theouter cuff550 may include more orfewer notches553 than shown, and the number of notches does not need to match the number ofcells312 in the row of cells positioned adjacent the outer cuff. If a relatively large total distance is cut out from theproximal edge552 ofouter cuff550 bynotches553, a relatively large amount of material of the outer cuff will become puckered, creating additional channels for blood to flow acrossstruts312cand312d. However, if too much of the fabric ofouter cuff550 is puckered, the resulting prosthetic heart valve may require greater forces to collapse and load into a delivery device and may even require a larger size delivery device. It should be understood that theouter cuff550 ofFIGS. 6A-B may be used with thestent402 ofFIG. 4A, rather than withstent302. Ifouter cuff550 is used withstent402, the extra material of the outer cuff in the puckeredportions555 may nest with the bowed struts412cand412dofstent402, similar toouter cuff350 shown inFIG. 4D, to help reduce the forces encountered upon loading the prosthetic heart valve includingouter cuff550 into the delivery device in a collapsed condition.

Still further, althoughnotches553 are shown as triangular in shape, other shapes may be suitable. For example, rectangular or trapezoidal shapes may be suitable for thenotches553. However, triangular shapes may help produce a substantially continuousproximal edge552 as the bases ofnotches553 are closed, while at the same time minimizing the size of any gaps that may be formed and through which blood may escape from betweenouter cuff550 andinner cuff306. The size of the notches may also be varied to alter the characteristics of the resulting puckeredportions555. For example, a smaller notch would result in a smaller puckered portion compared to a larger notch. A greater number of smaller notches could therefore result in many smaller puckered portions, while a smaller number of larger notches would result in a fewer larger puckered portions.

One example of an alternate configuration ofouter cuff550 is shown asouter cuff550′ inFIGS. 6D-F.Outer cuff550′ is similar or identical toouter cuff550 in all respects other than the positioning ofnotches553′, and the resulting position of puckeredportions555′. Whereasnotches553 ofouter cuff550 are illustrated as being in substantial axial alignment with the peaks ofdistal edge558,notches553′ ofouter cuff550′ may be positioned in axial alignment with the valleys of the distal edge. When thenotches553′ are gathered, for example in the same manner as described with respect tonotches553, puckeredportions555′ are created, much the same as puckeredportions555. However, because of the alternate positioning ofnotches553′, puckeredportions555′ are created in axial alignment with the valleys of thedistal edge558 ofouter cuff550′, as shown inFIG. 6E. As a result, when coupled to a stent and/orinner cuff306 as shown inFIG. 6F, the puckeredportions555′ are positioned betweenstruts312c,312dof acell312 across which the free distal edge ofouter cuff550′ extends. In other words, puckeredportions555′ are positioned between adjacent attachment points S1 of thedistal edge558 ofcuff550′ to the stent in a circumferential direction of the stent. It should be understood that the variations described with respect toouter cuff550, for example in terms of the size and number ofnotches553, may apply with equal force toouter cuff550′, including in terms of the size and number ofnotches553′.

The solutions described above may help create greater billowing of theouter cuff350 in the presence of retrograde blood flow, and hence greater sealing of the outer cuff against thenative valve annulus250. Still other features may be provided in order to assist theouter cuff350 from billowing outwardly, for example at a position adjacent to attachment points S1 where thedistal edge358 of the outer cuff is coupled to thestent302 and/orinner cuff306.

FIG. 7A illustrates anouter cuff650 that may capture the retrograde blood flowing past attachment points S1 while enabling that blood flow to enter the space betweenouter cuff650 andinner cuff306 in the restricted space RS betweenstruts312cand312dofadjacent cells312 in the proximalmost row of cells.Outer cuff650 may be used instead ofouter cuff350 with aninner cuff306 and a stent similar or identical tostent302.Outer cuff650 has a straight inflow orproximal edge652, correspondingly angled side edges654 and656, and a scalloped outflow ordistal edge658, and may be formed from any of the materials noted above for forming the other cuffs described herein, either from a single piece of material, from more than one piece of material, or as a single tubular member. Alternatively,outer cuff650 may have a substantially straightdistal edge658.Outer cuff650 may be wrapped aroundstent302 withedges654 and656 sutured or otherwise attached to one another. Theproximal edge652 ofouter cuff650 may be attached to the inflow end ofstent302 and/or toinner cuff306, for example by a continuous line of sutures, so that theouter cuff650 is positioned at any height between the proximal and distal edges of the inner cuff. Preferably, the attachment points S1 couplingouter cuff650 tostent302 and/orinner cuff306 are positioned at the peaks of distal edge658 (whendistal edge658 is scalloped), with the troughs not being directly coupled tostent302.

Outer cuff650 may additionally include a plurality ofapertures653. In the illustrated example, oneaperture653 is provided for each peak in thedistal edge658 ofouter cuff650. Eachaperture653 may have a substantially triangular shape with a base of the triangle oriented substantially parallel to theproximal edge652 ofouter cuff650, and a vertex of the triangle positioned closer to thedistal edge658 of the outer cuff. Theouter cuff650 may be formed without theapertures653, which later may be cut, stamped, or otherwise created in the outer cuff. If each peak in thedistal edge658 is coupled to thestent302 and/orinner cuff306 at a point S1, as shown inFIG. 7B, and eachaperture653 is positioned just proximal of each peak, each aperture will also be positioned just proximal of an attachment point S1. With this configuration, retrograde blood flow flowing past an attachment point S1 may be able to enter anaperture653 and flow into the space betweenouter cuff650 andinner cuff306 in the restricted space RS between thestrut312cof one cell and thestrut312dof an adjacent cell. As a result, retrograde blood flow entering between theinner cuff306 and theouter cuff650 in the region between two adjacent attachment points S1 may cause the portion of the outer cuff between thestruts312cand312dof asingle cell312 to billow away from the inner cuff and thestent302. On the other hand, retrograde blood flowing past an attachment point S1 and entering restricted space RS throughapertures653 may cause the portion ofouter cuff650 between thestrut312cof onecell312 and thestrut312dof an adjacent cell to billow away from theinner cuff306 and thestent302. Accordingly, the structure ofouter cuff650 enables retrograde blood flowing past attachment points S1 to be captured and the outer cuff to billow outwardly around the entire circumference ofstent302 to improve sealing upon the implantation of the prosthetic heart valve in the native valve annulus.

It should be understood that althoughapertures653 are shown as being substantially triangular, other shapes may be suitable. For example, a rectangular shape, a circular shape, a semi-circular shape, a crescent shape, a trapezoidal shape, or one or more slits in the outer cuff material in the circumferential direction may allow blood to enter the space between the outer and inner cuffs. The size ofapertures653 is preferably large enough so that retrograde blood flow may enter the space betweenouter cuff650 andinner cuff306, but not so large so that blood betweenouter cuff650 andinner cuff306 may readily escape through the apertures. In one example in whichapertures653 are triangular, the apex of the triangle closest to thedistal edge658 may be spaced apart from thedistal edge658 between about 0.05 inches and about 0.15 inches, preferably between about 0.07 and about 0.1 inches. In some examples in whichapertures653 are triangular, the base of the triangle may be between about 0.1 inches and about 0.2 inches long, preferably about 0.15 inches long. However, it should be understood that these dimensions are exemplary and may vary based on certain factors, such as the size of the prosthetic valve incorporating theouter cuff650. Additionally, theapertures653 are preferably positioned in the distal half or distal third ofouter cuff650 in the axial direction so that the apertures are closer todistal edge658 than toproximal edge652. This will enable the retrograde blood to flow into and occupy a greater portion of restricted spaces RS. It is preferable that some axial distance be maintained between thedistal edge658 at attachment points S1 and theapertures653. If there is only a small amount of material axially separating anaperture653 from an attachment point S1, there may be a risk thatouter cuff650 may tear between the aperture and the corresponding attachment point. The triangular shapes illustrated may help maximize the strength of the remaining material between anaperture653 and thedistal edge658 of theouter cuff650, while also maximizing the size of the aperture, particularly along the proximal base of the triangular shape, through which retrograde blood flow may pass. Although theapertures653 are illustrated with a triangular shape, it should be understood that one, two, or three of the vertices of the triangle shape may be rounded to eliminate a sharp angle at the corresponding vertex. For example, one or more vertices of eachaperture653 may be triangular with a rounded vertex having a radius of curvature of between about 0.01 inches and about 0.03 inches, preferably about 0.02 inches. Such a rounded vertex may reduce stress concentrations compared to a vertex having a sharp angle, which may in particular reduce the likelihood of theouter cuff650 adjacent a vertex of atriangular aperture653 tearing, including in particular the vertex positioned closest to thedistal edge658 ofouter cuff650. It should further be noted that theapertures653 inouter cuff650 may be combined with thenotches553 inouter cuff550, and thatouter cuff650 may also be used withstent402 instead ofstent302.

It should be understood that although the embodiments ofFIGS. 4A-D and5A-B each show struts being bowed inwardly to create space between an outer cuff and the curved portions of the struts, similar results may be achieved be providing the opposite curvatures in the struts, to create space between an inner cuff and the curved portions of the struts. Similarly, although the embodiment ofFIGS. 5C-D illustrate reducing the thickness of struts on an ablumenal surface of the struts to create space between the outer cuff and the reduced thickness portions of the struts, alternatively the thickness of the struts may be reduced on a lumenal surface of the struts to create space between the inner cuff and the reduced thickness portions of the struts. Forming the struts with the curvature and/or reduced thickness shown inFIGS. 4A-D and5A-D may be preferable to such alternative embodiments, however, as the embodiments ofFIGS. 4A-D and5A-D may provide for better anchoring and increased loading forces.

According to a first aspect of the disclosure, a prosthetic heart valve for replacing a native valve comprises:

• • a stent extending in an axial direction between an inflow end and an outflow end and having circumferential rows of cells formed by cell struts, the stent having a collapsed condition and an expanded condition;
  • a valve assembly disposed within the stent;
  • a first cuff disposed on a lumenal surface of the stent; and
  • a second cuff having a proximal edge facing toward the inflow end of the stent and a distal edge facing toward the outflow end of the stent, the second cuff being annularly disposed about one of the circumferential rows of cells and positioned radially outward of the first cuff and the stent;
  • wherein an ablumenal surface of selected cell struts forming the one circumferential row of cells has a concave curvature in a length direction of the selected cell struts when the stent is in the expanded condition; and/or
  • each of the selected cell struts has end portions and a center portion between the end portions, with the stent in the expanded condition a radial distance between the ablumenal surface of the center portion and the second cuff being greater than a radial distance between the ablumenal surface of each end portion and the second cuff; and/or
  • a lumenal surface of the selected cell struts has a convex curvature in the length direction of the selected cell struts when the stent is in the expanded condition; and/or
  • each of the selected cell struts has a substantially constant strut thickness in a radial direction of the stent; and/or
  • a lumenal surface of the selected cell struts is substantially straight in the length direction of the selected cell struts when the stent is in the expanded condition; and/or
  • each of the selected cell struts has end portions and a center portion between the end portions, the end portions and the center portion each having a strut thickness in a radial direction of the stent, the strut thickness of the center portion being less than the strut thicknesses of the end portions; and/or
  • the concave curvature extends along an entire length of the selected cell struts; and/or
  • the concave curvature extends along less than an entire length of the selected cell struts.

According to another aspect of the disclosure, a prosthetic heart valve for replacing a native valve comprises:

• • a stent extending in an axial direction between an inflow end and an outflow end, the stent having a collapsed condition and an expanded condition;
  • a valve assembly disposed within the stent;
  • a first cuff disposed on a lumenal surface of the stent; and
  • a second cuff having a proximal edge facing toward the inflow end of the stent and a distal edge facing toward the outflow end of the stent, the second cuff being annularly disposed about the stent and positioned radially outward of the first cuff and the stent, the second cuff including a plurality of notches at spaced apart locations along the proximal edge, each of the notches defining a void in the proximal edge of the second cuff, the second cuff having an initial configuration in which the voids render the proximal edge of the second cuff discontinuous, and a gathered configuration in which the voids are closed so that the proximal edge of the second cuff is substantially continuous, the proximal edge of the second cuff in the gathered configuration having a length that is less than the length of the proximal edge of the second cuff in the initial configuration, the second cuff being coupled to at least one of the stent and the first cuff so that in the expanded condition of the stent, the second cuff is in the gathered configuration; and/or
  • with the proximal edge of the second cuff in the gathered configuration and the stent in the expanded condition, the second cuff includes a plurality of puckered portions, each of the puckered portions being aligned in the axial direction with one of the notches and extending farther radially outwardly from the stent than portions of the second cuff positioned circumferentially between adjacent ones of the notches; and/or
  • a plurality of attachment points at which the second cuff is coupled to at least one of the stent and the first cuff, each of the puckered portions being positioned between a pair of adjacent attachment points in a circumferential direction of the stent; and/or
  • the stent includes a plurality of circumferential rows of cells, the second cuff being in radial alignment with a proximalmost one of the circumferential rows of cells; and/or
  • each of the puckered portions is positioned circumferentially between a pair of adjacent cells in the proximalmost row of cells; and/or
  • each of the notches has a triangular shape in the initial configuration of the second cuff; and/or
  • portions of the proximal edge of the second cuff adjacent each of the notches are coupled to one another in the gathered configuration of the second cuff.

According to yet another aspect of the disclosure, a prosthetic heart valve for replacing a native valve comprises

• • a stent extending in an axial direction from an inflow end to an outflow end, the stent having a collapsed condition and an expanded condition;
  • a valve assembly disposed within the stent;
  • a first cuff annularly disposed on a lumenal or ablumenal surface of the stent; and
  • a second cuff having a proximal edge facing toward the inflow end of the stent and a distal edge facing toward the outflow end of the stent, the second cuff being annularly disposed about the stent and positioned radially outward of the first cuff and the stent, the second cuff including a plurality of apertures; and/or
  • a plurality of attachment points at which the second cuff is attached to at least one of the stent and the first cuff, each aperture in the second cuff being aligned in the axial direction with a respective one of the plurality of attachment points; and/or
  • each of the apertures has a triangular shape; and/or
  • the triangular shape of each of the apertures includes a base oriented substantially parallel to the proximal edge of the second cuff and a vertex positioned closer to the distal edge of the second cuff than to the proximal edge of the second cuff; and/or
  • the stent includes a plurality of circumferential rows of cells, the second cuff being in radial alignment with a proximalmost one of the circumferential rows of cells, and each of the apertures in the second cuff is positioned circumferentially between a pair of adjacent cells in the proximalmost row of cells.

Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. For example, any dimensions provided herein should be understood to be exemplary in nature. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims. For example, features of one embodiment described above may be combined with features of other embodiments described above.

Claims (4)

The invention claimed is:

1. A prosthetic heart valve for replacing a native valve, comprising:

a stent extending in an axial direction between an inflow end and an outflow end and having circumferential rows of cells formed by cell struts, the stent having a collapsed condition and an expanded condition;

a valve assembly disposed within the stent;

a first cuff disposed on a lumenal surface of the stent; and

a second cuff having a proximal edge facing toward the inflow end of the stent and a distal edge facing toward the outflow end of the stent, the second cuff being annularly disposed about one of the circumferential rows of cells and positioned radially outward of the first cuff and the stent;

wherein an ablumenal surface of selected cell struts forming the one circumferential row of cells has a concave curvature in a length direction of the selected cell struts when the stent is in the expanded condition, and

wherein each of the selected cell struts has end portions and a center portion between the end portions, and when the stent is in the expanded condition, a radial distance between the ablumenal surface of the center portion and the second cuff is greater than a radial distance between the ablumenal surface of each end portion and the second cuff,

wherein a lumenal surface of the selected cell struts is straight in the length direction of the selected cell struts when the stent is in the expanded condition.

2. The prosthetic heart valve ofclaim 1, wherein the end portions and the center portion of the selected struts each have a strut thickness in a radial direction of the stent, the strut thickness of the center portion being less than the strut thicknesses of the end portions.

3. The prosthetic heart valve ofclaim 1, wherein the concave curvature extends along an entire length of the selected cell struts.

4. The prosthetic heart valve ofclaim 1, wherein the concave curvature extends along less than an entire length of the selected cell struts.

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